Bio 2 quiz 1

What do all life on earth trace back to?

LUCA (last universal common ancestor)

What are the 3 domains?

Bacteria, Archaea, Eukarya (eukaryotes)

Why is all life monopheletic?

Because we branch off from a single LUCA.

Why do organisms have more similarities with their recent ancestors than with their distant ancestors?

Organisms share more traits with recent ancestors because they inherit more shared characteristics. Over time, genetic changes accumulate, creating more differences from distant ancestors.

Synapomophies

Characters/traits shared with ancestors

Why are ancient traits found in multiple groups, while recent traits are limited to one group?

Ancient traits appeared early in evolution, so they were passed down to many descendant groups. Recent traits evolved later and are only found in the group that formed after the trait appeared.

What are the 4 kingdoms in the eukaryote domain?

Animal, plants, fungi, and protist

Ancient synapomorphies

Traits shared with other with other domains

Examples of ancient synapomorphies for eukaryortes?

• cell membrane is similar to bacteria

• DNA replication, transcription, and translation is similar to archaea

Recent synapomorphies

Traits unique to a domain only

Examples of recent synamorphies for eukaryotes

• chromosomes are in the nucleus

• have mitochondria

• Can perform meiosis

What ancient synapomorphies do bacteria share with other domains?

• 1 naked circular chromosome + additional small circular DNA called plasmids

• no histone in chromosomes

• formyl methionine amino acid in protein polypeptide chain

What recent synapomorphies do bacteria have?

Cells walls with peptidoglycan carbohydrate

How did cyanobacteria change Earth’s atmosphere?

Cyanobacteria used photosynthesis to produce oxygen as a byproduct, leading to the accumulation of O₂ in Earth's atmosphere

What recent synapomorphies do archaea have?

Phospholipid membrane with branched hydrocarbons & can live in extreme environments (extremophiles)

What are some ecological impacts of bacteria?

• Cyanobacteria reduce atmospheric CO2

• Used in Biotech for drug, food and chemical production (e.g. insulin from genetically altered E. coli bacteria)

• Contaminated site cleanup (e.g. marine bacteria “eat” oil spills)

• Beneficial bacteria (e.g. probiotic bacteria) vs pathogenic bacteria (e.g. Strep) affect health

Why don’t antibiotics harm human cells?

Antibiotics target bacterial-specific traits, such as penicillin disrupting peptidoglycan synthesis and preventing cell division & tetracycline inhibiting bacteria specific ribosomes and preventing protein synthesis

What is the endosymbiotic theory for the origin of mitochondria?

The endosymbiotic theory states that mitochondria in eukaryotes originated from aerobic proteobacteria. Evidence includes mitochondrial DNA similarity to bacterial DNA, a double membrane structure, and mitochondria dividing by binary fission before the host cell undergoes mitosis or meiosis.

What does new molecular data suggest about the evolutionary relationship between the three domains of life?

That all three domains (Bacteria, Archaea, and Eukarya) branched from a common ancestor, LUCA, at the same time, meaning Bacteria is not the ancestor of Archaea and Eukarya.

What is FECA

First eukaryotic common ancestor

How did the first eukaryotic common ancestor arise?

Through a combination of archaea and proteobacteria

(1) True or false: many steps happened in evolution from FECA to LUCA

True (1)

How many branches did FECA branch into and what are the main ones?

FECA branched into multiple lineages, but this course mainly focuses on plants, animals, and fungi

How did eukaryotic plants contribute to life on land, and what is their current role in Earth's biomass?

They were the first group to colonize land, establishing the base of the food web for other organisms like animals and fungi. Today, land plants account for 80% of Earth's total biomass.

What evidence supports the endosymbiotic origin of chloroplasts in plants?

• similarities in DNA code to photosynthetic cyanobacteria

• the presence of a double membrane

• the process of binary fission in chloroplasts before the plant cell divides by mitosis or meiosis.

What adaptations do land plants have to survive on land, and how do these help them deal with the challenges of dry environments?

• cuticle and stomata to reduce water loss

• cellulose to support structure without water buoyancy

• embryo retention in seeds for reproduction in dry conditions.

What are the 2 major taxa of land plants?

• Vascular plants - bigger & independent of water and has vessels for transport

• Bryophytes - smaller & dependent on living near water and have no vessels for transport

how do bryophytes and vascular plants reproduce?

Both reproduce through alternation of generations, where spores grow into gametophytes, which produce gametes for fertilization, resulting in a zygote that grows into a sporophyte.

What are the dominant stages for the 2 taxa of land plants

• Bryophyte - gametophyte

• Vascular plants - sporophyte

What made vascular plants (angiosperms & gymnosperms) successful on land?

have evolved pollen for cross-pollination and seeds to nourish the embryo during germination.

What characteristics make flowering plants (Angiosperms) highly successful, and how do they reproduce?

Flowering plants (Angiosperms) are highly successful due to their flowers, which enhance cross-pollination and genetic diversity with the help of animal pollinators like bees. Additionally, fruits, which develop from the flower’s ovaries, surround seeds and encourage seed dispersal when animals eat the fruit, helping to move seeds away from the mother plant.

What are the different functions of fungi?

• Decomposers - absorb broken down nutrients from dead material (leaf litter)

• Parasites - take nutrients from living hosts (only fungi benefit from this)

• Mutualists - Form symbiotic relationships with host so both sides benefit (fungi provides phosphorus to host and host provides sugars to fungi)

(2) True or false: some fungi are unicellular but most are multicellular

true (2)

Hyphae

Network of tiny filaments that make up the fungal body

Chitin

A structural polymer similar to cellulose found in the cell walls of hyphae

Mycelium (mycelia)

Refers to large network of hyphae

Mushroom

Above extension of hyphae used for reproduction (need to spread spores because hyphae is not exposed to outside air)

Spores

Germinate into new fungal hyphae

How do fungi obtain nutrients, and what roles do they play in the ecosystem?

Fungi obtain nutrients by secreting hydrolytic enzymes that break down large molecules into smaller ones, which are then absorbed through the large surface area of their hyphal network.

• Some fungi can digest cellulose (the most abundant plant matter) and lignin in wood, playing a crucial role in breaking down dead plant material (ex. Saprophytic fungi)

What is the role of mycorrhizae in plant growth, and how do plants and fungi benefit from their mutualistic relationship?

Mycorrhizae are fungal mutualists that form a close association with plant roots. The fungi's hyphae, which are finer than root hairs, absorb soil nutrients like phosphorus more efficiently and provide this excess phosphorus to the host plant. In return, the plant supplies the fungi with sugars. This mutualistic relationship allows plants with mycorrhizae to grow better than those without, due to improved nutrient absorption from the soil

How can fungi have harmful effects, and what are some examples of fungal diseases?

Fungal diseases can damage or kill crops, leading to significant harvest losses. Additionally, mycosis refers to fungal infections affecting animals, including humans.

What are the synapomorphies of the Animal Kingdom, and how are animals related to fungi?

The Animal Kingdom is a monophyletic group closely related to fungi. Animals share two synapomorphies: they are mobile as adults and/or larvae, and they ingest food rather than absorbing it through cell membranes like fungi.

What unique features distinguish animals from other organisms?

Animals are unique as they have nerves, which transmit information, and muscles, which create motion.

How does animal phylogeny illustrate the evolutionary progression of body structures?

Animal phylogeny shows a progression from multicellularity to radial symmetry and then to bilateral symmetry

What are the three key traits that drove animal diversification, and how did they contribute to evolutionary complexity?

1. Multicellularity – Allowed early animals to evolve from small forms into larger, more complex life-forms.

2. Muscles – Enabled efficient movement, improving food gathering and survival, with coordination by the nervous system.

3. Bilateral symmetry – Allowed for directed movement, leading to cephalization, the development of a defined head with a brain and sensory organs for better environmental interaction.

   1. Simple animals like sponges had radial symmetry

What are the four key traits that differentiate animal taxa?

1. Body Plan – Symmetry determines complexity and mobility, with asymmetrical animals (e.g., sponges) being simple and sessile, while bilaterally symmetrical animals are more complex and mobile.

2. Reproduction – Animals reproduce through internal or external fertilization and may provide varying levels of parental care.

3. Sensory Systems – Different sensory adaptations help animals forage, avoid predators, and find mates.

4. Nutritional Mode – Animals ingest food using diverse mouthparts and process it through internal digestion.

How do viruses compare in complexity to prokaryotes?

Viruses have simpler structures than prokaryotes

Why is the classification of viruses as living organisms debated?

Viruses are debated as living organisms because they are not considered cells and cannot reproduce independently. They are also obligate intracellular parasites, meaning they require a host cell to replicate.

What are the main structural components of a virus?

1. Viral genome – Made of either DNA or RNA.

1. Protein coat (capsid) – Surrounds and protects the genome.

2. Membranous envelope (some viruses) – an outer envelope derived from the host cell

What are the main steps of viral replication?

1. Entry – The viral genome enters the host cell and remains separate from the host genome.

2. Replication – The viral genome is copied using the host’s DNA replication machinery.

3. Protein Synthesis – The viral protein coat is produced using the host’s transcription and translation machinery.

4. Self-Assembly – Viral parts assemble into new viral offspring.

5. Release – The newly formed viruses exit the host cell, often destroying it in the process.

How do the release mechanisms of non-enveloped and enveloped viruses differ?

• Non-enveloped viruses typically cause host cell death through lysis, as the cell bursts to release new viruses.

• Enveloped viruses usually do not kill the host cell immediately, as they are released more slowly through budding. During this process, each virus takes a piece of the host’s membrane with them

Why are antibiotics ineffective against viral diseases, and how does the body defend against viruses?

Antibiotics have no effect on viral diseases like COVID, influenza, or the common cold because they target bacterial structures, not viruses. Vaccines help by training the immune system to recognize and fight viral invaders, providing immunity against specific viruses.